Casey Station Bathymetry Survey 2014/15 (GA-0348/ AAD 3326)

Brief description

The Casey Station Bathymetry Survey was conducted last summer from December 2014 to February 2015. This collaborative survey was undertaken by Geoscience Australia, the Royal Australian Navy and the Australian Antarctic Division, using the AAD's workboat the RV Howard Burton. The survey goal was to acquire high resolution bathymetry data to improve our understanding of the seafloor using multibeam sonar. The bathymetry data collection will be supplemented by physical sampling of the seafloor sediments and video recordings of the biological communities living in the seafloor. The survey will cover areas that haven't been charted during the 2013 Casey Survey and are frequently used by the RSV Aurora Australis.
Improving our understanding of the seabed environment in these shallow coastal waters will ultimately lead to a better environmental management of the Australian Antarctic Territory. The data will also help the RAN to develop more accurate navigation charts therefore reducing the risk to maritime operation in the region.

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Maintenance and Update Frequency: asNeeded

Statement: The casey Station (Antarctica) Bathymetry Survey, GA-0348/ AAD 3326 was acquired by Geoscience Australia, RAN and AAD onboard the RV Howard Burton from the 23rd of December 2014 to the 27th of January 2015.

This dataset was acquired and processed by IXSurvey and further processing was conducted in the office by Michele Spinoccia, using CARIS HIPS & SIPS ver 7.1.2.
1. First a vessel configuration file was created where the co-ordinates of the motion sensor and DGPS antenna and patch test offsets were recorded.
2. A new project was then created and the vessel configuration file was attached to the project file.
3. The raw swath sonar data, in raw.all format, for each line was then imported into the project and the vessel information assigned to the data.
4. The motion sensor, DGPS and heading data were then cleaned using a filter that averaged adjacent data to remove artifacts.
5. Different sound velocity profiles data for each block were attached to the corresponding raw swath sonar data files to correct the depths for changes in the speed of sound through the water column.
6. Then a new blank field area was defined that specified the geographic area of study and the co-ordinate system used. The co-ordinates for the study areas were WGS84 UTM-49S.
7. The data was cleaned by applying several filters that removed any remaining spikes in the bathymetry data using user defined threshold values. A visual inspection of the data for each line was then undertaken where artifacts and noisy data not removed by the filtering process were removed manually using Swath and subset editors modules of the Caris HIPS/SIPS software.
8. All the data for each bathymetric, motion sensor, DGPS, heading, tide and sound velocity profile data were merged to produce the final processed data file. A weighted grid of the processed data was then created for each Block.
In GA the tide was applied to the grid to correct for tidal variations and velocity corrections were performed to correct for different artifacts and mismatches.
9. The processed data was finally exported as grids soundings or false colored images for presentation and reporting and as final processed data in in ASCII XYZ as well as geotif formats of 1m resolution.
10-Using CARIS Base editor 4.0 the grids were exported as ESRI ASCII grid, then imported into ARC catalogue/info to create a raster file for the entire survey.
11. New version was created using Caris v11.3.16 to reference vertical datum to EGM2008 and horizontal datum to EPSG 4326 and gridded according to AusSeabed banded depth definition (AusSeabed_DepthRanges_2019.txt).